jusplainwacky

Hello -

I'm having a heck of a time figuring out what is going with my spark plugs.

Here is the setup -

327 block with 283 heads
WCFB carb
Hydraulic lifters
Autolite 86 Plugs

Here is the scoop...Excuse the length.

My car has been sitting for a while, but before it ran great. Now it will hardly idle. It runs rough and blows out "blackish" smoke. Many times it will die while idling.

Although the car did run great, I have made some changes...one is that I converted an original distributor to a Protronix point-less distributor and spark wire/plugs.

While running my engine, I ran out of gas and in my haste I "may have" grabbed a gas can that had a 40:1 (2 cycle) mix and put perhaps a couple of gallons in the car. I do not believe however the car ran rough right after that. It seems to me that it ran rough just before I ran out of gas.

I put in about 5 gallons of new gas and its still running rough. I have twice removed the plugs, wire brushed them, sprayed them with carb cleaner and put them back in the engine...it starts right up, but give it a minute and it starts running rough again.

Also what is strange is that the engine sounds really loud...as if the internal workings are really noisey...I let it idle for at about 15 minutes and reved it up several times..it revs right up. Then all of a sudden it all quited down..which I don't get...it sounded fine...running smooth.

Then I start it up the next day and it starts all over again...same thing. I remove the plugs and the plugs have a flat black (almost like powder coating on them) yet the threads are oily wet.

Since my car is up on blocks, I could get under the engine and listen and I could swear the loud sound was in the oil pan area, but then if you listen from on top of the car, you swear its in the intake manifold.

I decided to remove the oil pan...the pistons looked great, the cylinder walls look great (could see the cross hatching)...everything was nice and tight and it looked great.

I also tried to adjust the 2 screws on the throttle body down to the point the car would barely run and that didn't change anything, however at that point the plugs have been already fouled beyond recovery.

I have a couple of questions...

1. Why would the engine sound loud if the plugs are fouled? It almost sounds like something ratteling...but then cleared up at one point.
2. Are both the screws on the front side of the carb mixture settings? Why two of them? Is it because the carb is basically two carbs in one housing as I was reading online?
3. Once plugs are fouled...can they be ruined and no matter how much you wire brush them and spray them?
4. Are Autolite 86 plugs "OK" to use - is there something better?

Below is a picture of one of the plugs.

Thanks for your time...again appologize for the lenght..but better to tell it all here instead of asking questions that I haven't answered.

wombvette

Sounds like its flooding to me.

jusplainwacky

I thought that also....but what seems "strange" is that it did and has cleared up...then it's back to square one. I would think that if it was flooding, that it wouldn't just clear up....but then again...sometimes it just won't clear up.

I did rebuild the carb and maybe some "junk" is making the valve stay open.

Is there a way to tell if its flooding without having to take the carb apart?

wombvette

Black plugs and black smoke are a pretty good indication.

w1ctc

Check to make sure that its not flooding bad enough so gas ends up in the oil and thins it. That could cause the engine noise.

Dan Hampton

The rattling is more than likely due to a misfire on one or more of the cylinders. Once you have that issue cleaned up that should go away. Replace the plugs with the AC46

Bill Irwin

The good news is... its not oil fouled, the bad news is... it's carbon.
Your plugs are way to cold and you way to rich. , change to AC 45 or 46 and lean the carb. Bill

1955 copper

Your floats may need to be readajusted , see pic. The two screws on the Carb side are inspection screws to check float level . So put a rag under the screws and remove them while the engine is running .
1. If gas pours out the floats are to high (fouling plugs)
2. The gas level should be right at the bottom hole level
2 If ether is not correct remove the top and readjust the floats.
3. If your corvette floods out on left HARD turns see how to fix it.
4. two screws at the front do nothing when you add RPM , they are air-fuel mixe at idol only
Hope this may solve the problem

Procrastination Racing

Ton of stuff here.

283 heads on a 327 can be all sorts of issues, but without knowing all about the engine, no one can really say. What are the head chamber sizes? what are the valve sizes? This could have octane requirements higher than the octane you are running.

The electronic ignition you have is the same one that has a list of frequent problems. The points ran good for 20 years in small blocks until they came up with the HEI, but they did require maintenance.

You could have firing problems.

The spark plugs look too cold from the color. Like everyone said, get some hotter plugs. Probably a set of AC R-46 since it is not likely you can find AC 46.

if you ran a mix of oil in there, then you have lots of blackness to work through. Hopefully, it is a small amount, and if so, either dump it (not easy) or fill the tank with good gas. You may need a higher octane than you have been running.

The idle jets have been all screwed up. With bad gas, you will never get them set, so you have to get that out and have fresh plugs to even think of adjusting them. Basically, you can use 1-1/2 turns out on each as a starting point. Set that, then set the idle speed screw to make it idle.

To run, a dual plane intake has a barrel that feeds each plane. And that barrel needs to be adjustable, so the left and right front barrels each have an idle adjustment screw on the front at the bottom. You want this in to lean it out at idle as much as possible and still maintain a smooth idle. Adjust speed with the idle speed screw on throttle, not the idle screws.

You do not need one on the rear barrel(s) because they are closed at idle speeds.

If you have an oil mix gas, you will have a rattle. Don't rev it high but you need to burn all the old gas out.

I hope you didn't remove anything inside other than the oil pan.

Fouling plugs is not fatal. However, wire brushing can deposit enough metal on the porcelain insulators for the high voltage to leak down the side and cut the spark considerably. Long ago, there were spark plug cleaners which sandblasted the insulator and electrode which prevented metal contamination.

jusplainwacky

Hey Everyone...thanks for all the information!

There is a lot of information here in one night to sift though so bear with me while I absorb it all.

Just a couple of things to answer some questions. The car has always had a 327 block with 283 heads and ran fantastic. Some hotrod'ers do this because it really up's the compression ratio. I have never had to run high octane in it and it never ping'ed.

I'll try the hotter plugs as suggested, check the jets, move the screws out (maybe start with just 1 turn)...and try some of the other suggestions. It might take me a few days to report back....but feel free to keep the discussion going.

Thanks again everyone!!

MikeM

The very FIRST thing I would do is check your fuel level in the carb as described above. Adjusting the carb, cleaning the plugs, etc is a waste of time if the float/fuel level is too high for whatever reason.

Many times when plugs get fuel fouled, they're done.

Frankie the Fink

First off there is nothing wrong with a properly installed Pertronix ignition -- I've run all three generations of them over decades with zero failures in cars I've beat on hard... Good luck finding ACR46S plugs (which are correct for early small block Chevy's in the first place). There is a service bulletin I have supporting this....I doubt you will find one of these plugs let alone eight. There are ACR46S equivalents from other vendors. The Autolite 86 plugs should NOT foul after a few minutes of running. They are crossovers for both the 45 and 46 plugs. It sounds like to me you got some 'junk' in your carbs possibly causing the needle valves in the carbs to constantly dribble and never really shut off until the crud got cleared out. (I had identical symptoms to yours when my '61 continually fouled -- turns out the WRONG needle valves were in the car. I respect Roy ('55Copper) opinions greatly but I have nearly every old piece of documentation for WCFBs and the side screws are not referred to in a single one of them. When I set my 6-1299 carbs exactly to specs and took the side screws out the fuel was not at the bottom of the screw holes (similar to setting Holley floats). I know of no other way to check float level than to take the air horn off these carbs. There are two idle mixture screws simply because your carb has multiple barrels and the front two contain separate idle circuits. If you car is running fine now then cause-and-effect analysis makes me think its the two stroke oil you dumped in there. Its not inconceivable this screwed up the carbs enough to gas foul the plugs (even though a first reaction would be oil fouling.)

jusplainwacky

Hey Frank - Mike...

Good suggestions!

To give more clues....Right now the car runs like crap...constantly fouling. However one time it all smoothed out after running it a big and constantly reving it up...it sat there and idled fine, wasn't noisy and rev'd up great. However 99% of the time, it's running like crap, misfiring like crazy, black smoke coming out the exhaust. Then next time I start it....it's back to square one.

Also one thing I didn't mention... last few times I have turned it off...it dieseled a bit.

In regards to Mike's comments....I'm thinking along the same lines. I could go buy new plugs, clean the carb, etc...but if its flooding, then it would be a waste of time.

ON THE OTHER HAND....(I feel like the scarecrow on the wizard of oz...could be this, could be that)....

Lets say that it was the 2-cycle gas...and I foulded the plugs and perhaps also gummed up the carb in some manner and it has nothing to do with the floats, needle adjustments or whatever in the carb?

A part of me thinks this might be the case, because when I first started up the car after putting in the pertronix, distributer, etc....it ran great...sounded strong and purred.

A part of me thinks maybe take off the glass filter bowl...and put in some carb cleaner in it (or the tank), change the plugs. and fire it up and see what it does...but then on the other hand I'm thinking it also could be a waste of time and plugs, but it would be a quick thing to do.

1955 copper

The side screws are old school info , that's why there is no info on them in books. But it's a starting point inspecting float level . weak coil going out can also be the problem.

65tripleblack

Agreed that the carb is too rich as evidenced by the dry carbon deposits.

The Autolite 86 plugs are an EXCELLENT choice, as they cross to an AC R45S (extended tip). As long as your pistons clear the electrodes without closing them, then the extended tip is very beneficial, as it gets the kernel of the spark closer to the center of the combustion chamber for a faster burn..............ultimately requiring less spark timing.

I'd be interested to hear some more feedback on the oily wet threads. I assume that the OP has no external oil leaks flowing onto the spark plugs.

jtranger

Look down the throat of the carb while it is running at idle. If you see any fuel dripping in the carb it is and needle and seat flooding problem.

MikeM

I'd forget about the 2 cycle gas mix causing the problem. That by itself won't cause your symptoms.

After you eliminate the high fuel level in the carb, whether it's dirt in the needle/seat or a bad float/float level, then go the that Pertronix. Put points back in the distributor and see if your problem goes away.

jusplainwacky

JT..thanks for the tip...I'll see if I can look inside.

As far as the Protronix...I don't think that is the problem. I have a timing light and its solid 4 degrees on the timing tab...it doesn't bounce around. I also have an oscilloscope (not engine scope, but actual oscilloscope) and the timing marks look all the same height. Lastly...it ran great with the pertronix and it rev's right up when it starts to clear up.

JohnZ

That's another clue. Dieseling ("run-on") is usually caused by having the throttle plate open too far at idle, which causes it to idle on the transfer slots (which is WAY rich) instead of on the idle mixture orifices, and it can fuel-foul the plugs. If it doesn't respond well to adjusting the idle mixture screws (or refuses to die when you turn both screws in to the seats), then you know for sure it's idling on the transfer slots.

jusplainwacky

Hey John....

Ok...ya lost me. What is the "throttle plate" and "transfer slots"?

And you are correct....I saw a some change when adjusting the screw on right (drivers side when facing the engine) and not much on the left. I could actually stall the car with the one on the right...not sure on the one on the left..I didn't play too much with either. However, with the car running like crap, it was hard just to get it to idle much less have time to really play with the settings.

I did notice this...with the engine off and looking down inside the carb...I pump the accelerator rod and only the right side squirts out gas and the left side only dribbles out. Another clue??